Very much up to the individual - though quite a few people have chosen to do the same units (GD, 9th SS, S.Staffs etc etc)
When we were a Kingdom it was run by a King
When we were an Empire it was run by an Empress
Now we're a country we're run by a..........
i went for a british airbourne esk uniform, with no insignia currently, which could also be used as a brit commando, sas trooper, or the intended paratrooper. hope this helps!?
You could always annoy the majority of the forum users and join the 101st 
Show me a man who will jump out of an airplane, and I'll show you a man who will fight!
General James M. Gavin
CRY HAVOC AND LET LOOSE THE DOGS OF WAR
Admiral Akbar says ITS A TRAP !
I thought the majority of users were 101st? 
I would suggest coming to a couple of events in "counts-as" kit, i.e. whatever you can scrape together that looks vaguely ok and build up your gear as you go along.
That's what we did/are still doing.
Second that Pilgrim!
No point waiting until you have pukka kit else you will be missing out on what really matters, playing the game.
Stage 1 starter level brit kit.
Maroon beret.
Belgian Denison (You should be able to borrow one of these - we've got one you can use anyway).
Webbing - belt, cross straps plus 2 pouches (£15ish from Sabre Sales).
Any old olive drab trousers (which you have already?).
Puttees (£2 local army surplus store - surplus gaiters aren't much more but you won't get them to fit around modern boots).
Any black boots (which you have already?).
That will be enough to look the part and get playing. It's what we started out with.
However, if you want to join the PBI I think they operate a kind of minimum level which will mean you need to invest in a bit more stuff when you can. Note though that if you borrow the denison at first then you won't have wasted any money on counts as kit, except the puttees. You can then move on to -
Stage 2
Proper denison (current advice is to get the Soldier of Fortune half zip one for £100).
Battledress trousers (we got 49 pattern for £12 but these aren't quite right).
Gaiters (£3 at Sabre Sales).
DMS boots (£15 from Sabre Sales - these also aren't quite right but we use them).
At this point you've got the choice of spending more on proper trousers and boots and moving onwards and upwards. Someone else will have to advise you on that because we're still at Stage 2.
With 49 pat trousers looking at them would it be possible to remove the pocket and restitch it into the correct position ?
yes... but you also need to add another pocket on the right hand side... the smaller FFD pocket.
Other mods needed are:
- removal of belt loops
- removal of the left pocket from the back
- move the slit side pockets (not sure how)
but all those are less important than the two pockets on the front... I certainly didn't bother when I used to wear 49 pat
