Here are some of my favourites:
See if this menu is to your tastes:
http://bistro1.co.uk/...t-bistro1-restaurant/
If so, take a look at the amazingly low prices here:
http://bistro1.co.uk/...london/covent-garden/
(There's a service charge to be added to those prices, but it's still cheap).
Bistro 1 is definitely one of favourite places in London!
http://bistro1.co.uk/...urants/covent-garden/
Otherwise Porters is reasonably priced:
http://www.porters.uk.com/
The Lyceum Tavern offers good pub grub upstairs. (The menu isn't particularly adventurous, with the usual pies, chilli, fish & chips, etc but the prices are cheap).
http://www.telegraph....um-Tavern-London.html
The Lemon Tree is a lovely little gem, offering great Thai food (and other dishes) at reasonable prices:
http://www.yelp.co.uk/biz/lemon-tree-london
I was in Covent Garden yesterday. I opted for the Lyceum Tavern but you'd probably like any of the above. If you like Thai food though, the Lemon Tree might well be your best bet.
Chris