Alternatives to the ADV were considered on more than one occasion if I recall correctly. F-14 and F-15 before the ADV was ordered, as FB says, F14 fitted the bill for a long range interceptor for the Northern UKADR but was too expensive. F15 was acknowledged as an excellent fighter but lacking a Nav/RIO/WSO was not thought suitable for the all weather interceptor role (this was the A model).
I think an offer of F15s was made at a later date that involved the US buy of Tornados for the Wild Weasel role as an offset (The figure of 80 Eagles sticks in my mind). I think this was when delays started to appear in Typhoon.
Michael Portillo considered an F-16 lease as a stop gap for Tuyphoon when Defence Secretary