Uefa delegates will be asked to expand more than their waistlines when they gather in London ahead of the Champions League final. They will also be invited to enlarge Europe itself. At Friday's annual congress, representatives of the continent's national associations will vote on whether to widen Uefa to include a 54th member, one whose application has been the subject of bilious arguments for over a decade: Gibraltar.

Gibraltar's first application, in 1999, was rejected in the face of intense opposition from Spain, which claims ownership of the tiny territory and is fearful that if Gibraltar were to be admitted to Uefa, then it would set a precedent that could inspire similar claims from separatist Basque or Catalan teams.

The last time there was a vote on the issue, in 2007, only three countries supported Gibraltar's application and the Spanish Football Association remained so hostile to the proposal that they threatened to withdraw all Spanish teams from Uefa competition if Gibraltar got in. This time, Spain may be unable to keep Gibraltar out, even though Uefa rules, which were introduced following pressure from Spain, restrict membership to sovereign states recognised as such by the United Nations.

Gibraltar has been under British control since the 1713 Treaty of Utrecht and Spain has been demanding it back since shortly after that. The UN classifies it among the world's 16 remaining "non-self-governing territories", along with territories such as the Falkland Islands and Western Sahara. So it is not a sovereign nation.

The thing is, the court of arbitration for sport ruled, first in 2007 and then again in 2011 following an appeal, that Uefa cannot refuse Gibraltar entry on those grounds because Gibraltar's initial application was made before the introduction of the sovereignty rule. Following that ruling, Uefa granted Gibraltar provisional membership, enabling it to enter national teams in under-17 and under-19 tournaments for the first time.

If they secure permanent membership on Friday, Gilbraltarian clubs will enlist in the 2014-15 Europa League and Champions League, while a senior national team will take part in the Euro 2016 qualifiers. Gibraltar need a simple majority and believe they will get it. "We are quietly confident that the vote will go in our favour this time," says Dennis Beiso of the Gibraltar Football Association (GFA), who has spent the last three months travelling around Europe trying to rally support.

"Each and every one of the countries we have visited has said they are ready to welcome us into the family. It is a completely different ball game this time. The last vote was held less than a month after [the first Cas ruling] so we had hardly any time to put forward our case and most countries, to be frank, didn't have a clue what Gibraltar had to offer and had only been exposed to one side of the story."

So what does a 6.8sq km disputed territory with a population of 28,000 – slightly less than that of San Marino – have to offer?

"We are a small country with a big passion for football and deeply-rooted league pyramid," says Beiso. That pyramid includes two divisions comprising 17 clubs (such as Manchester United, Chelsea, Boca Juniors and FC Hound Dogs). The Gibraltar Manchester United point out with pride that Sir Matt Busby gave them permission to use that name when they were founded in 1957. With similar pride, the GFA highlights the fact that it was founded long before that, in 1895.

Gibraltarians have been keen to stress their football heritage in the run-up to Friday's vote. "Ours is not a tinpot league and we are not a flash-in-the-pan federation," says Beiso. "We have a long engagement with football. We meet the entry criteria and we want to be in for the same reasons that the 53 other associations want to be in, and that is to further develop the game in our country."

Gaining fully-fledged Uefa membership would give a huge stimulus to the game on the Rock, starting with the construction of a new 8,000-capacity national stadium in time for the Euro 2016 qualifiers.

"The main thing is the grassroots development," says Beiso. "Being allowed in would bring valuable resources, not just financial but also technical. For example, at the moment the 10-strong committee that makes up the FA are all volunteers. That would change. But most of all, we could bring in more coaches. The lack of such expertise is a serious problem in the development of the game, so to bring in coaches would be of great benefit to our children. Also, although our players have natural ability, they had never had a shop window to show themselves in. They would get that."

Gibraltar would be the smallest but not, they believe, the worst team in Europe. A 3-0 friendly win over Faroe Islands last year hardened that conviction, although they do not suffer from delusions of grandeur. "Look, we know we're probably not going to win the World Cup any time soon but we can be one of the more competitive minnows," says Beiso.

"Look at teams like Liechtenstein and Andorra. When they first came in they were getting beaten 10-0 or whatever, and sometimes they still are, but with experience and better organisation they have got to the stage when they can give teams very good games and we may follow a similar pattern."

It would be interesting to see what would happen if they were pitted against the current European and world champions, for more than one reason. "We just want to play football, we do not want to get involved in political arguments," says Beiso. "We have no issue with anyone and would be happy to play any of the 53 members that we get drawn against."