Omio is a travel booking platform which serves mainly UK and Europe. It is kind of an all-in-one platform where you can book train, bus and flight, and from many different operators.
As it is only an agency, the prices you get are unlikely to be any cheaper than from the official site or other agencies. However, Omio tends to run ludicrous offers on Cashback sites (especially Topcashback) which gives you a very nice rebate on the fare paid.
There is a very good offer going on at the moment (expiry unknown):
15% cashback on training bookings is excellent. I’ve used Omio for UK train tickets a couple of times and I didn’t have any problems. From my experiences prices are the same with the official channel, although Omio does charge 50p service fee per booking.
5% cashback on flights is also very good by industry standard. However I have no idea how good or bad their prices are, and I recommend against booking flights via ANY third party at the moment.
Remember though, that cashback is never guaranteed. If yours doesn’t track, file a claim afterwards, but that doesn’t mean it’s certainly going to be resolved either.
If you are interested, you could use my referral code kaiz9x6h4l7u when joining Omio. This gives you a welcome voucher of €10 on a booking of €40 or more (converted to GBP at the current exchange rate).