Peter Capaldi says playing the Time Lord is 'very intense' and hopes his portrayal brings back 'mystery and strangeness'

The new series of Doctor Who will see the Time Lord join forces with Robin Hood and be injected into a Dalek, but its star Peter Capaldi has revealed his deadliest foes – tight budgets, BBC politics, and the paparazzi.

Capaldi, who will be seen in his first full episode in the role when the show returns to BBC1 on Saturday, said he was still finding his feet as its 12th Doctor.

The former Thick of It star said he wanted to bring back some of the Doctor's "mystery and strangeness", which he said was hard in a 50-year-old show, with an approach that was "serious … but still quite comic", a "more grown up Doctor" who was "still mirthful".

"I don't know if it's quite fallen into place yet," Capaldi told the new issue of Radio Times after seven months making the show. "I'm trying all the time to see what works and what doesn't work.

"Doctor Who is a very intense working experience because, like most things at the BBC, there's not quite enough money and money is time and there's really not quite enough time to do it, so you are always on the hoof, pedalling as fast as you can."

One of the BBC's most expensive shows – as well as its most money-spinning – series showrunner, Steven Moffat, has talked about how "extraordinarily difficult" it was to make its feature length 50th anniversary special on an hour-long budget last year.

Capaldi, the oldest-ever Doctor at 56, said he had been given advice about his new role by his predecessors, Matt Smith and David Tennant.

Asked what they had told him, Capaldi said: "Sometimes you're in the middle of a big production that has a lot of BBC politics and administration at work and it's a big commercial vehicle.

"But you're an actor and sometimes have to compare notes to see how the others might have felt about the things I am going through or am being asked to do. It's good to be able to chat to people who have been in the same situation."

Capaldi said he had a "big talk" with his wife, TV producer Elaine Collins, before accepting the role.

"David and Matt made clear to me that there are things that will change, that you have to be prepared for, like your visibility," he said. "I was happy walking down the street doing what I want to do without having paparazzi there. We agreed there'd be pluses and minuses but so much of it was unknown."

The much-anticipated new series will see the Doctor join forces with Robin Hood in an episode written by Sherlock co-creator Mark Gatiss. In another episode, the Doctor and his assistant Clara are miniaturised so they can go inside a Dalek that is "so damaged it has become good", said Moffat.

Capaldi said he was shocked when he first entered the Tardis to find "it was just like a wardrobe, like something your dad had made. And there was a prop bloke and a smoke machine. When I had to step out of it, it was quite nerve-racking, but delightful as well."

The 12-part series will also feature the "the deadliest bank in the cosmos", manned by a terrifying creature called the Teller; a Frank Cottrell Boyce episode in which the trees claim back the earth; and "Mummy on the Orient Express", guest starring Frank Skinner.

Other guest stars will include Keeley Hawes, Sanjeev Bhaskar and Ben Miller. Another episode, featuring Hermione Norris, is set on the moon.

A childhood fan of the show, Capaldi – most recently seen on BBC1 drama The Musketeers – said he "never thought" he would be in the frame for the role "because the Doctors were getting younger and younger and that was fine".