I'm sorry I don't speak French, but hope this helps anyhow :)
There are a huge range of hostels in Scotland - both members of the SYHA www.syha.org.uk and independent ones. Prices seem to be in the range of £8-£18 a night, but it depends on the size and facilities. If you are able to cook for yourself that will keep costs down but there are a wide range of take aways etc.
If you are interested in to North West Scotland and would like to see some gorgeous wild country then the SYHA hostel at Loch Ossian is well worth a visit - you can only get there by train it is so remote. It is £15 a night.
Another amazing place in the north west is Knoydart - reachable by boat from mallaig. For details of places to stay there have a look at www.knoydart-foundation.com
Hope I've understood what you are looking for - have a super trip.