Hello mate.
From personal experience there aint many decent firms left in London anymore.
Most are full of c.unts who couldn't scaffold a bus-stop, but are either friends of friends, drinking/charlie snorting buddies with the supervisors or just grasses...
But there are some fairly decent paying sites in and around London, most are Agency work - Not great as its temporary work, but atleast you know where you stand.
Heres a few you could try:
ATR Fusion (Brendan) - 0845 241 1230.
BMSL (Cliff) - 0207 826 4400.
Forefront (Lee) - 01709 376 386.
On-Site (Sarah) - 02392 893 145.
Coyles (Leighton) - 0208 901 6626.
If not, do a gooooooogle search for Construction Recruitment Agencies in London.
Though having said that,
GKR Scaffolding and
Loughlin Scaffolding were both looking for Scaffolders the other day, both advertising in the Metro and Evening Standard.
Id also try to get your Part 2 Basic Scaffolding ticket sorted as well, as most firms will want that as a minimum now days for a new starter.
I hope this helps mate.
Good luck.
Jay.