Hey bro, I'm in the UK too. London town. Why on earth would you buy hash? There is so much good prime green bud around. Even "good hash" isnt great and it kills your lungs to smoke it.
If you cant find the seed, leave it in the soil. If you didnt end up burying it too deeply, you might just see it pop out. If you bought the seed from a shop chances are its quality and will germinate in the soil. But even if it is a seed from a baggie you bought to smoke, you could still get lucky.
I found the best way to germinate is the wet paper towel method. Although some water in a cup works just ast well. The reason I like the paper towel method is, you can put it just about anywhere and no need to worry about spills. You can also easily check for when it is ready. With the water method, once the seed sinks to the bottom and stops floating, its a good sign that it is absorbing water and a high chance that it will live if you plant it.
Take a look at my journal here
https://www.rollitup.org/grow-journals/323218-complete-newbie-first-grow-ever.html. The very first picture you see is a seed that was done via the paper towel method, and one day after I put it in some soil from my back yard it popped up just like you see in the pic.
I've never done a MJ grow indoors before, but have loads of experience in growing veggies and fruits on the farm. So take it from me, in future avoid the disappointment and germinate your seeds before you put them in soil. Its not a requirement as seeds will germinate in moist soil as well, but by doing it before you put them in soil, you can eliminate any dead seeds.
Also patience, patience, patience. Could take 1 day, or 10 days. It all depends on the age, quality, and other conditions such as temperature etc. But if in another week, you dont see any sign of life, its a pretty safe bet it may be lost.