1. Soho walk ups (from £22 for 10 mins)
2. I've a AW hotlist at £40/30 mins. Have gone to see Xena a couple of times and good VFM:https://www.adultwork.com/2486447
The rest of the £40 hotlist is untested (and fairly uninspiring) but can pass on if interested (a AW search will produce similar results anyway)
3. Budget parties: LAPC £60 for 3 hours, LSAP £100 for 4 hours
While these may tip you over budget slightly the longer duration and extra action (hopefully) while you're there might keep you going slightly longer until the next urge to punt.