Hey Tee098,
I'm assuming you're looking at the University of York, but I will give some advice as a York St John Student who takes Politics. Personally, I would look at doing your year at Loughborough.
The reason is, as you mentioned, is that you can gain experience of the subjects so you know what you want to tailor towards. If you feel that economics is still something you wish to do, it means you can get an insight into that. As well, if you wish to transfer, you will be more likely to achieve it if you can prove you are achieving the grades in your current modules from 1st year, rather than just A levels alone; you will have to speak to their admissions team on what they are looking for. Overall, you might find you actually really enjoy the course and wish to stay. At the same time - don't feel obligated to remain with your course if you really feel its not for you.
The other part to bear in mind is that I am going to assume you have accommodation at Loughborough, obviously, this will be an entire task in itself to deal with.
On the other hand though, if you really did want to take a gap year, it means you can work up any finances ready for university; obviously, you will need to decide soon, as your student finance will likely have come out to pay the university - I think theres only so long before it officially goes through and you can't claim it back.
But to convince you of York, it is honestly a great city. I came from a not-so-great area, and so when I came to York, it was like everything was just gold compared to previous. It's got a lot of stores, so if you like shopping; definitely consider. Otherwise, it's really well connected with trains, buses etc. You can get to Leeds on the train/bus for about £3, as well as Scarborough for £3 on the bus. There's a good range of activities, and honestly, it's just a nice place. Really good for cycling routes as well.
Hope this helps.
Koen.