I don't think that I'll be about that weekend but if I am I'll let you know.
You can launch in the town itself (Weymouth) and cruise through the Old Harbour into Weymouth bay.
https://www.weymouth-harbour.co.uk/daysailors/
You can see a couple of photos of the slip on Boatlaunch, don't know how busy it gets at the Bank Holidays as my boat is round the corner at Portland.
As well as the other slips the article mentions you can also launch at the National Sailing Academy at Portland. Handy if that's where your daughter is sailing from. (Ferrybridge and Castletown are also around that way)
I don't know of anywhere that offers to launch for you so you would have to launch yourself but the town slip is wide and well sheltered and the trailer parking is right at the top of the slip although there are limited spaces.
Let me know if you want any more info on these or other options.
Steve