I used Stormsure Waterproof repair glue (see Amazon) to repair a torn cycling jacket, an Aldi one but the basic material appears to be similar to the
Altura.
Cost is around £5.50 from several retailers but you either pay a low unit price and high delivery or high unit price and low delivery.
This stuff is foul, make sure you are in a short sleeve shirt (that you don't mind losing) have a damp j-cloth to hand and a match stick type implement that you will also throw away after use. probably need to put a sheet of newspaper down as well.
Read the instructions for the best mend, you need to gain access to tear from the underside if at all possible (unpicking the lining or cutting the lining and sewing it up afterwards (the aldi jacket had a mesh liner).
You temporarily fix the tear from the outside with sellotape, apply the glue from the rear and allow to set then peel off the tape. The fix melts the nylon/neoprene/ripstop material into a weld.
You can fix the tear from the outside using this stuff but it will not look as good.
My effort was not pretty (mostly through not reading the instructions properly and not wanting to cut the lining to gain access to the rear of the tear, and sew it back up, if this is an option I recommend you do it) I fixed an L shaped tear on a sleeve approximately two inches on each side.
Or as mentioned you can take it to a menders ;-)