Hi Iain
The Broads are not noted for their marinas! Boats mostly moor up alongside the banks/staging with no mod. cons. I wouldn't recommend a visit during the school holidays as it will be heaving and finding anywhere to moor overnight will be a nightmare. Best out of season. The only places I can think of to launch are all attached to boat yards, which you will need to contact in advance to get permission. We have launched (a Wayfarer) from Stalham and Martham Boat Yards on the northern Broads and the Waveney River Centre at Burgh St Peter is the nearest you'll get to a 'marina' on the Broads - not sure if the slip will take a P21 but worth a try - but I think it will be fully booked this summer.
Another suggestion to anyone with a trailer/sailor - the Rivers Orwell and Stour in Suffolk offer some very protected sailing areas with the possibility of venturing out on the open sea through Harwich if you wish, with the River Deben and Walton Backwaters nearby. Several marinas with all facilities and some lovely quite anchorages/moorings. Our club, the Royal Harwich Yacht Club (based at Woolverstone, half way along the River Orwell, NOT at Harwich) has a very gentle concrete slip which is ideal for launching and recovering trailer/sailors (there is a P21 in the compound) and welcomes visitors (especially if you don't want to launch at a weekend, when things can be busy with dinghy racing). We even have a marina and the club may be able to offer you a temporary berth if one is available. Just give us a call or contact the club directly.
Anne and Dennis Kell, yacht Redshank P275
East Coast reps. - details in the handbook