You've got Billy and Gyp asking if they can come now. It's a fair step for us though.
You can of course take the train to Weston-super-Mare then the Somerset Coaster bus (First Bus service 20) to Brean Village Hall. From there its a walk of about 1.5 miles to Brean Down. A walk that can be done along the beach.
Said bus service is usually operated by open top buses and runs until 28th October 2018. Runs hourly Monday through Sunday (half hourly Mon-Sat until 1st September).
https://www.firstgroup.com/bristol-bath-and-west/routes-and-maps/somersets-coasterEDIT: Posted as you posted grahame. I see you've done the above in the past.
I of course drive across Somerset to get to Brean Down. Public transport for me would be bus, bus, bus or bus, train, bus. bus.