You must go through immigration and pick up your bags and clear customs, then head down the channel for Domestic flights to recheck them. So it really depends upon the lineups in immigration and if your domestic flight leaves from the new terminal or the old one. Expect at least 20-minutes to a half hour most times to clear immigration, another 15-minutes to wait for and ride the train to the luggage/customs hall. Then 10-15 minutes to recheck your bag and get to the Domestic terminal in the new complex, or about a half hour wait/ride time to get to the old terminal, then allow time for security. It will be tight but should be able to do it. What time of day are you arriving?