If your TV receives the channels you should be fine.
For what it's wprth, I am also considering doing this but the information website shows that I also will only be able to receive 20 channels. This is clearly rubbish because I already get all freeview channels via my smart tv, a fact confirmed by the freeview site when I looked on there. I did put a note on the forum but the only advice seemed to be that I should list the channels! This does cause me concern because I would have assumed that BT would have checked freeview availiabillity via the freeview site using the information I gave them - so I have no idea why it is different if I check myself. Not convinved by BT at all.