I'll get the ball rolling
One website that has saved me loads of money is called
www.toptable.co.uk which allows you to book a restaurant at your chosen time, provides you with all the info you need such as dress code, reviews, interior etc and on top of that, they provide you with some of the best exclusive offers in 1000's of restaurants in the UK.
Not only that but every time you use Toptable and you provide a review (star ratings is acceptable but you can write a brief review if you want) they'll give you points which you can then use to receive free meals at selective restaurants.
I've been using Toptable for around a year now and it's been great, literally saved me many £100's and had a great time knowing the best places to take my gf.
Hope that helps everyone that likes going out for a cheap meal or even luxurious restaurants.