Question Author
Thanks, guys!
The tricky bit is to sort out the models which say they can do leather and those that really can do leather. I looked at those which gness suggested but they seem to come on their own table etc which my daughter declared too big for the space she has, plus you never really know how much remaining life is left in a second-hand machine.
Good news is that she has sorted it herself - for the record, she decided on a portable sold by Sailrite in Portsmouth. As it name suggests, it claims to be man enough to cope with sails and other heavy-duty materials, so fingers crossed it will do what she wants. It is pricey and I have volunteered to go halves. Sailrite also sells a 'beef-it-up' unit for similar machines from other makers. Hope the information is helpful to anybody else coming across this in years to come.
Cheers, everyone, thanks again!