Hmmm, well I wasn't there right from the beginning, so my perspective won't cover everything.
MFUK was started by a great man, sadly departed, by the name of Bob Nicholls, in Cardiff, Wales. This was all officially done with FASA's backing and we ran tournaments all over the UK mainland for us Battletech enthusiasts. Membership was the same as the US Mechforce and an annual stipend netted you the usual type of stuff: membership card, certificate of enrollment into your chosen faction's military, tournament rules of engagement, and a quarterly magazine called Comnet. We also did patches, dice, variant 'mech models, variant 'mech record sheet books, scenario books, reference tables (look-up charts), etc, etc.
We arranged group travel to GenCon in the US for those members who could afford it (I remember a hazy drunken week in Chicago and Milwaukee, and netting second place in the Solaris Gunslinger, even though I had no idea what I was doing at the time). We also started to see coach loads of our German brethren arriving at the UK's bigger events to take the coveted MFUK awards back to the Fatherland. I think that was before Mechforce Germany took off big style.
As for products, hopefully the OP will add the list of MFUK products he has to this thread.