There's loads of advice on here RE how to cover up. Infact, there's an entire thread called something along the lines of 'Its summer time' (I can search for it later if you can't find it)
Cocoa butter and bio-oil and any other cream for stretch marks could help long-term. Or steroid cream from your GP depending on the type of scarring that you have. Short term, Primark sell really cheap and thin long sleeved tops. And foundation could help, depending on the typr of scars again. Also, tubi-grips are wonderful!