For your satnavs West Street is BS2 0DF but coming from the Evening Post
roundabout there is quite a long loop round the one-way system until you
head back from the far end of West Street - but parking is free on Sunday!

There is an NCP ('Bristol Broadmead') facility behind the Marriott hotel
with up to 9 hours at £7.80

If you're staying at hotels, they have own spaces or cheaper deals at NCP.