Are you dreaming? No.

You won't know until you give it a go!
a bit of hard work to start with (uphauling), but the first time planing never leaves you.

ptsf1111 said..
Sure you can! You might want to consider taking a lesson or two for a great initial experience and learning the basics.. For learning you need a very big board and a tiny sail.

True that! By "big board" it doesn't need to be very long, but a nice wide board gives good stability when up-hauling. Massive difference between beginners' boards available now compared to the old 'windsurfer' style of old!
And I believe windsurfing to be one of the best activities you can do for all-round fitness & fun, so go for it!

Thankyou everyone,
I loved hearing all your supportive messages and sooo much wisdom in them all.
Technique
-Don't fight the wind
-Learn sail control first
-Become ambidextrous and don't go think you can do everything one way and get stuck. You must've seen people do this.
-Lesson's to start
- learn slow and steady
Info on gear selection
- 140 litres at least
- 6 metre sail
- start with big board and small sail then move onto small board with a big sail
- width gives stability not all about length
- Stay away from Gumtree
Support
- Age is no barrier
-78 year old is doing it
- Wife started at 50
- Windsurfing is fun and good fitness
- Hip issue is not a major hassle like other sports
And with a bit of hard work and start with uphauling and then the feeling of planing will never leave me.
Thanks everyone that is all I needed to know to start my journey.

Weight should not be such an issue, but consider your local spot.
Ocean and waves choose your preferences
but flat water lakes, bad wind consider foiling as your goto path. Board size does not matter that much and sailsize is reasonable.

For normal windsurfing at 100+ I had to use my small sail was 7qm, standard 8 and lighter winds(15kn) 9.5qm. This also stretches the limits of most sail components and you will break some stuff. You will also switch to smaller boards soon and hate them, as they stop going for you in any lull. Some charts say roughly +10kg = +1qm.

For foiling I can use my 'small' 7 as lighter wind option. And a lot more days to enjoy the watersite. Boards are modern (even used), typically large(140l+). Wind limit is down to ~10kn.

Practise a bit with a friend or school on a huge board, 5-6qm Sail and some wind to see if you like it and afterwards choose your path and weapons.

Hey, Windypete, how's your quest going? You might be out there progressing by now, but here's a couple more thoughts if you're not doing it yet: you might find it hard to get to your feet to uphaul the rig if you can't easily get up off the floor at home due to dicky hip. (Kitesurfing is easier with limited mobility, as the kite pulls you up onto the board, and the board is also much lighter to carry around.) Even if you can do this, it'd be good to avoid abrasive deck grip on your board in order to preserve your skin! EVA foam is a much friendlier option for beginners.