Erm - all of them. GB has had its foreign policy defined by trade - the opening of new markets, the protection of existing markets and the protection of their links.
Kick off with the Napoleonic wars. Napoleon wanted to extend the French Empire and influence, he saw England as his main threat (as did Tsar Alexander - Treaty of Tilsit). They then divided Europe between themselves. French stranglehold on Europe threatened not only GB trade with Europe, but also its sea lanes to the colonies - hence the Peninsular War.
The bulk of the other European wars in the 19th Century, as I recall, did not involve GB, or a threat to GB markets, as they were between city states and 1 country v another, as neither side was actually trying to build a complete domination of Europe and thus threaten our trade. The 2 closest threats on mainland Europe, were the year of Revolutions, 1848, but the GB govt stepped hard on any potential insurrection and relaxed some laws to keep the public sweet & the Franco Prussian War, 1870, which was based around who owned Alsace - Lorraine (I will have to review this to confirm my hazy schoolboy history lessons!). This did not pose an immediate threat, in fact it benefited GB, because it meant that we could continue our overseas annexations, whislt our competitors squabbled over old ground. (BTW Germany did not truly become a nation until 1871) So they were in the throes of trying to het their act together and really came late to the Imperial race.
In the 20th Century we know about WWI & WWII. Both were really fought against German expansionism and domination of Europe. Now I'm not saying that these were trade related, but they were a direct threat to Britain and its trading partners and allies.
I'd like to add that I'm an atheist and do believe that religion is the root of all evil, but I also believe that we should try to review our actions as honestly as possible. In short was GB wrong in building an Empire - No. It needed new markets and resources, like all other countries going through growth & industrial reformation. Has GB used religion as a pretext for war - yes, is this right, I don't think so, but it's a bit late to argue the toss. Is Religion a useful thing - No, but it is so entrenched in society that we might as well break it down and start again, but then what would replace it? People do seem to need to believe in somebody else guiding their destiny.