For anyone sailing in the UK, if only for a weekend, it’s hard to beat the Solent. It’s a nice stretch of protected water, flanked by the flat (and in some places industrial) coastline between Portsmouth to Lymington and the rolling hills of the Isle of Wight.
You charter in a ton of places. I strongly recommend Sunsail in Port Solent. It’s big organization that charters dozens of boats. They are well-organized. We chartered a Sunfast 37 a couple of times. It’s fast but sturdy and well-equipped for a cross-channel crossing if that’s what tickles your fancy. The only downer is that it’s a long way up the river from Portsmouth which can be a bit of a pain.
The Solent can get pretty crowded in the summer but it’s quite entertaining getting caught up in the races. 
You also see some lovely boats of all shapes and sizes. The best thing is the annual Round the Island Race in June with 1500 boats on the line doing the 50 miles around the IOW. It’s fantastic fun.
Everyone goes to Cowes which if you didn’t know already is a yachtie mecca. I prefer Yarmouth. It’s smaller, more down-to-earth and there is always a great atmosphere in the jam-packed harbor. Tip: It has very good showers and excellent pubs.
Here is a nice post on an English guy’s blog about his weekend on the Solent
The Western Isles of Scotland kick the Solent into touch. Less busy, eyepopping scenery, cheaper. Not as eay to get to, and prone to rain.