My general understanding is that, when taking off, landing, and practicing approaches, (intentional go-arounds) at a licenced airfield, you are exempt from the 500', and the 1,000' rule.
When taking off and landing at an unlicenced airfield, you are exempt from the 500', but not the 1,000' rule.
That is correct (but insert "Government or" before unlicensed airfield. You need to obtain a written permission from the CAA to land at an unlicensed site in a congested area. £113 per application at the last count. I have a folder full of them.
Judging by past experience, most people don't seem to bother do so (or even understand the requirement) but you may be prosecuted if you don't get the permission.