Most of the UK options are reactive to what Germany did/built G1.
If Germany built a carrier and 1-2 tpts (Sea lion?) then as the UK you take out the Italian dd/tpt in sz96 w/air power (hope they miss). NCM all fleet to sz 92 (Med & anything left in the Atlantic), leaving the UK dd from sz98 in sz94 to block out the Italians (French in sz93 completes the block out). You could also bring ground or AA to Gib to attempt to get them to London when your facing Sea lion, and use your fleet as best you can on UK2. The Italians can take Algeria giving the Luftwaffe a landing place after an air assault on your navy in sz92, but they will be out of position for Sea lion, and down a few planes. If they don’t attempt to kill your fleet maybe place it in sz110 to force the Germans to hit it as they Sea lion (changing the odds of the amphib), or force them to amphib from sz109 (or abort). If they go around to sz 109, then you have lost London, but the German fleet is more vulnerable to a counter attack. Hopefully your US ally was paying attention, and may have some air power to weaken the German fleet, and you can play clean up if they go through sz109.
If the Germans buy ground units (art etc…), then you have more options. Neutering the Italians early by taking out the their navy is a top priority. Hitting either sz95 or sz97 can be devastating to both, but the UK can recover much easier, or replace losses w/Indian ships. You can also use the S African IC, or build an IC in Egypt to rebound. I personally have had some bad experiences as UK attacking the Italian navy UK1 (who hasn’t), so sometimes I’ll just set-up defensively, and let them take themselves out. If the Germans G1 buys point to Barbarossa, then you have to control Italy, protect the Middle East (oil), be ready to def US landings, and have units ready to aid Russia from India/Egypt (Mid East).