Be careful.
I once had a bad experience..
When superseal liners came out, my merchant told me these were the new liners and you dont need the old type ones. So i used these liners on a compression fitting under a bath. It held for about 6 months then popped off!!!
Brought the living room ceiling down. Turns out the old type liners are for compression and superseal are for push fit fittings only. Apparantly the local water pressure increased after some work carried out on the main.
I'll never use plastic pipe with compression fittings again. Always put copper into the compression then plastic fittings onto the copper. This sometimes looks cack and can be expensive, but so is repairing ceilings