I am not so sure that you cannot cross a solid white line. This has caused a great deal of argument, can you...can't you!!
Crossing a solid white line
You MUST NOT overtake
if you would have to cross or straddle double white lines with a solid line nearest to you (but see Rule 129)
if you would have to enter an area designed to divide traffic, if it is surrounded by a solid white line
the nearest vehicle to a pedestrian crossing, especially when it has stopped to let pedestrians cross
if you would have to enter a lane reserved for buses, trams or cycles during its hours of operation
after a ‘No Overtaking’ sign and until you pass a sign cancelling the restriction
[Laws RTA 1988 sect 36, TSRGD regs 10, 22, 23 & 24, ZPPPCRGD reg 24]
Double white lines where the line nearest you is solid. This means you MUST NOT cross or straddle it unless it is safe and you need to enter adjoining premises or a side road. You may cross the line if necessary, provided the road is clear, to pass a stationary vehicle, or overtake a pedal cycle, horse or road maintenance vehicle, if they are travelling at 10 mph (16 km/h) or less.
[Laws RTA 1988 sect 36 & TSRGD regs 10 & 26]
So IF the traffic is stationary then it would seem that you may cross the solid white line, however once the taffic starts to move, no matter how slowly , you will be committing an offence...... unless of course the now moving traffic is is a pedal cycle, horse or road maintenance vehicle AND they are travelling at less than 10mph. However, beware as if you do have a collision whilst filtering and crossing a solid white line, the court may have little sympathy if you wish to bring a claim to recover compensation. The other problem is that there is also some confusion even with police officers, so you may be stopped anyway.
You may also wish to Google the following case to bring you up to speed on current case law:-
Jessop (by his mother and litigation friend Veronica Rundle) v Nixon
 EWHC 3211 (Civ) QBD (The Hon. Mrs Justice Smith) 14/12/10
However, I am pleased to say that every case is determined on its own merits