Advice on which Psu would best suit my 7750.

I'm running the exact same card in a mini-ITX system with an Antec 150W PSU. That doesn't mean you are in the clear though. I specifically designed every other component in the system to be low power.

The card pulls about 46W at load so you are probably OK. It might be a good idea to invest in a power meter like a kill-a-watt and measure your power draw before you install the card. That will give you an idea of how much headroom you have to work with.

If your 250 Watt power supply has a maximum combined +12 Volt continuous current rating of 17 Amps or greater it should work.

What is the brand and model number of your 250 Watt power supply unit?

You'll pushing that PSU to the max. I wouldn't recommend it. Even a 350 watts power supply would be able to run that card but i wouldn't risk it with a 250w one.

You don't know that. Until the OP tells us what model his PSU is then all we can do is guess.

The 7750 needs 43W or a little less than 4A at full peak to run (link). All of those amps must come from the +12V rail. We don't know how many amps he's got until he looks at the label. Even then, a less reputable PSU OEM will not be accurate or outright lie on the label. I would run a 7750 on a 200W SeaSonic, but I wouldn't run it on a 350W CoolMax.

For the record, my 150W PSU has only 10A on the +12V rail. Max system power draw measured at the outlet during gaming is 99.3W. But like I said before, I've got a reputable power supply brand and hand selected parts to fit in that power window.

XFX Core Edition Pro 450. Cheap, quiet, reliable, high quality, 5 year warranty and built by Seasonic.
Win, win, win and more win.

i've got GTR LC-B250SFX

Ive got LC-B250SFX. Thanks

That's a generic brand power supply with a maximum combined +12 Volt continuous current rating of 16 Amps. Whether or not that power supply is able to actually supply what is specified on the label determines whether or not it will work.

Yeah, not sure about that PSU.

Here's an excellent replacement SFX power supply:

SeaSonic SS-350SFE 350W SFX12V V3.1 80 PLUS Certified Active PFC Power Supply

It has 26A available on the +12V rail and will definitely work for the 7750.