As a follow on from my comments above, you do realise you will have to borrow a huge amount of money before you even open the restaurant.
I have never run a restaurant but my guess is you may need to borrow say £100,000 so you can rent the retail unit, have the kitchens and dining area fitted out and hire the staff (you have to hire and pay the staff even before the restaurants open and starts to make money).
So you could be £100,000 in debt before you even get your first paying customer.
Also note a number of large restaurant chains are in financial trouble, Prezzo for example have had to close 94 of its restaurants just to try and stave off administration.
https://www.bbc.co.uk/news/business-43259062
The restaurant business is cut throat, prone to failure and VERY hard work.
Think hard before you take that risk.
Maybe start small by cooking Mexican meals in you own home and selling them locally (home delivery?) and then see how the business grows.
Many cooks and chefs started this way and with the internet it is easier than ever to start a small business at home.