Parking at Avebury for Summer Solstice can be a nightmare. Ideally you get there before the NT car park opens at 9am or wait till after 7pm for the overflow car park (behind the Manor) to open. Even then there is very limited space.
If you find yourself unable to park at Avebury itself, the next option is the 49 bus.
Park in or near the Crown Inn, Bishops Caning SN10 2JZ. (They offer camping as well !)
Busses run every 30 minutes to Avebury ( Red Lion) take 10 minutes and cost £3 !
06:14 06:38 07:11 07:42 08:07 08:42 09:16 09:46 10:11 10:46 11:11 11:46 12:11 12:46 13:11 13:46 14:11 14:46 15:20 15:50 16:20 17:07 17:31 18:06 19:04 19:04 20:07 20:57 21:57 22:57