Transited both ways this weekend and do so reasonably regularly.
The VFR transit lane is clearly shown on the chart with the southern entry at Hemel and the northern entry at Pirton. You may find a short hold is necessary at either point. If you want to make the transit just take up an orbit and wait. Of course if there is much of a delay it is quicker to route east or west around the zone, as the zone is not large. Usually you will be asked to route behind any inbound traffic - "caution wake vortex" either below 2,000 or 2,500 feet or if there is no inbound traffic via the active threshold.
The controllers are pretty much all very good although there is the occasional one who is rather cautious.
As a general comment whilst transits have improved immensely we are still not that good at accomodating GA traffic in this country. I often feel that controllers could do with spending six months in the States!
If you are trasiting south bound and going any where east of Farnborough you might also want a SVFR through Heathrow. Unfortunatley you will rarely get a hand over at weekends (its better during the week), so you need to be ready to get a call in pretty quickly. Farnborough and Heathrow work closely so their operations appear more seamless and you will often get a retain Squawk and contact Farnborough etc.
Heathrow seem reluctant to handle more than one transit at a time as also does Luton. I am sure this never use to be the case??