Is it possible to just get all the sealing redone on windows?

External silicone seals around window frames can perish over time which can lead to water penetrating and causing damp patches. This can be prevented by removing old silicone using a shape putty knife and re-pointing with an adequate silicone seal.

Yes is a very easy job ive done many times just take a sharpe chiesal and small flat head screwdriver and just take it all out clean really well , go screwfix and by some frame sealant and re-do & will look great, Cheers

Yes it is possible, clean out the silicone and start again, on a lot of the older style windows you can pull the rubber seals out and buy new ones a wide range on eBay, just need to measure the size of rubber and match it up,