The single coil will affect your tone to some extent. It will be slightly thinner and possibly brighter but you can still get a decent tone.
The Marshall amp's voicing is not exactly the best for metal. You could try what ambush suggested. The metal zone has plenty of reviews and demo videos, check them out. It's been said to have a slightly thin tone, maybe it's not the thick tone you're looking for. You should, if possible, try it before buying.
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