Another big 'yes' for TAMCO. Trevor really does have the mando market covered in the UK. If you really do need a bluegrass mando with that woody chop sound that is so important for rhythm playing, then I think you need to narrow your choices a bit. A solid woods carved top and back is a must, and these don't come cheap unless from the Far East. F holes seem to be preferred (oval holes tend to have a more open, ringing sound; fine for old-timey and Celtic stuff, but hopeless for bluegrass.) The debate between A-model and F-model body shapes rages still, but my own view is that it matters less than carved bodies and f-holes.
There are some bargains to be had; Eastman mandolins just get better and better, especially their mid to high end models. Look for a high end A model for real value. Right at the bottom end, Ozark (read 'Samick, Korea') make a very nice solid wood F model called the 2255. Nothing fancy, but well made, easy to play, loud and barks like a hound dog. Needs heavy-ish strings and a heavy pick to make it work well, as you really need to 'drive' the top. I have one, and Chris Leslie from Fairport Convention swears by his. I tend to gig with mine ahead of some fairly expensive American jobs, as it's just so easy to play. See info here
As always, the best advice is 'play a few, find one that speaks to you'!
Tim