Prebuilds i don't know,but you could look at something like this,
PCPartPicker part list /
Price breakdown by merchant
CPU: AMD A10-5800K 3.8GHz Quad-Core Processor (£70.30 @ More Computers)
Motherboard: MSI A78M-E45 Micro ATX FM2+ Motherboard (£40.93 @ Amazon UK)
Memory: Kingston Savage 4GB (1 x 4GB) DDR3-1866 Memory (£23.12 @ CCL Computers)
Storage: Seagate Barracuda 1TB 3.5" 7200RPM Internal Hard Drive (£32.40 @ Aria PC)
Case: Cooler Master K350 ATX Mid Tower Case (£19.99 @ Scan.co.uk)
Power Supply: XFX ProSeries 450W 80+ Bronze Certified ATX Power Supply (£35.18 @ Ebuyer)
Optical Drive: Samsung SH-224DB/BEBE DVD/CD Writer (£10.06 @ CCL Computers)
Operating System: Microsoft Windows 7 Home Premium SP1 OEM (64-bit) (£67.95 @ Ebuyer)
Total: £299.93
Prices include shipping, taxes, and discounts when available
Generated by PCPartPicker 2015-07-04 15:57 BST+0100
I would have l;iked more ram in it since the internal gpu (igp) of that cpu doesn't have it's own vram.
even for looking yourself at a prebuild.I don't know the game so maybe it's more cpu dependent,but from what i read should this be about the best you can get for that budget.
Maybe look at a used machine too,someone who sells his old game pc.
Also post this on one of those Smite fora,they might have something to say about it.
Don't bump it's unnecessary.