Hi Jemma,
Bristol and Bath have regular mass monthly events which are held on either Saturdays or Fridays and include special guest teachers, live bands etc. The last event in Bristol was two night event held on the Friday and Sunday which included a one off guest appearance and show by the current World Champions from Columbia!
Unfortunately sometimes these events overlap like they did in July, but by all accounts both events were well attended. When the Bristol event finished some real salsa freaks ended up going to Bath as well which was on until 3:00 am!
Details about both monthly events can be found here.
The Bristol monthly events are at the Fry Club in Keynsham: www.salsabristol.co.uk/
The Bath monthly events are at Claverton Rooms in Bath University: www.salseros.co.uk/