Dear Nadine
Apologies for taking so long to reply to your mail. I’ve discovered this morning a batch of questions that, for reasons unknown, went into our ‘junk’ folder.  Yours was amongst them.
I don’t need to see comparison titles.  The reason some agents ask for them is that they help quickly to give a busy agent an idea of the sort of book you’ve written, and the market at which it is aimed.  If you’re able to communicate this info succinctly in a different way, that’s absolutely fine.
You are right in your instinct to err against appearing over-ambitious.  Many years ago I was lucky enough to work with a brilliant and experienced editor who used to warn against comparing a debut novel to a classic or a bestseller.  He said that, by doing so, you inadvertently set it up for a fall.  I’ve always felt those were wise words.
Polly