They're low end, but reviews seem to say they function fine and it means I don't have to spend time changing everything. The RD maybe a bit shit, but from a quick pull of the cables it moves. So provided it's straight and nothings chewed I should be able to get it to work. FD's are usually so simple that should be fine too.
Had a look on ebay and Altus shifters seem to be c.£15 so you may be right and just buying new shifters is the way to go.
https://www.ebay.co.uk/itm/Shimano-Altus-SL-M310-3x7-21Speed-Stainless-Steel-Cables-Shift-Set-for-MTB-Bike/184753184002?hash=item2b0425dd02:g:RHMAAOSwLxNgbroS
They're low end, but reviews seem to say they function fine and it means I don't have to spend time changing everything. The RD maybe a bit shit, but from a quick pull of the cables it moves. So provided it's straight and nothings chewed I should be able to get it to work. FD's are usually so simple that should be fine too.