28mm either Perry's or Front Rank, Foundry are also nice - they are designed by the Perry's and fill in the gap in the Perry range.You should also have a look at Fife and Drum -
http://fifedrumminis.blogspot.co.uk/ as they are superb figures.
15mm Old Glory and Peter Pig
As for rules British Grenadiers or Maurice are good for larger battles.
For skirmish, Sharp Practice or Musket's and Tomahawks - though
imo M&T is a rather thin game if you don't use the role play rules, a little too like the old Charles Grant rules in the Wargame - which is not a bad thing, it's just Grant's uses much larger units and provides a better spectacle.
To wit...