If you can buy the flights on one ticket, and get your luggage (if any) get send through, you may be alright and if you are delayed you will be put on the next flight with space. Remember that intercontinental flights will often be only once a day or even less, you may have to wait quite a while.
With separately bought tickets it is a risk I would not take at all. If your incoming flight is late, you will miss your expensive flight and its return (as missing one flight mostly cancels the whole itinerary) and that is a lot of money.
If you need to collect your luggage, you need to pass into the UK, which mostly takes a few minutes but can be longer for an EU citizen. Then you need to collect your luggage, again most often just a few minutes but if you are unlucky, you can have to wait quite a while like half an hour or even longer, just because there is a snag in the handling of luggage.
Then pass through customs, which again should not take time but might if they select you for inspection.
Then you have to make your way to the right terminal and the bag drop there, again not huge times but the little bits do add up.
Now the most important time, you need to be at the bag drop off before they close for your flight. That can be an hour, not sure.
From the luggage drop off you will have to make your way through security, and walk the length of the terminal in time to meet the boarding time.
Not impossible in two hours, but any snag will make you miss your flight.
I would advice against buying separate tickets, whatever the time between the flights, but if you have to, several hours more or overnight for a late morning flight will be acceptable.
And I would also advice against buying tickets from a site where they combine two separate tickets, not securing the connection for you.
Besides the risk of missing your connection and thereby the rest of the flights, often intercontinental flights with an extra leg are cheaper than direct flights from either European airport. It is worth checking more flights to see if a lower price is available for a single ticket for the whole travel. It might be worth to drive (or train) to a different airport and get a better ticket from there.