Your specs are somewhat incomplete so to properly recommend is a little difficult.
Not sure whether your graphics are from the integrated chip on the AMD A10-7860K APU or from a discreet card but either is weak. The 7860K is rather weak as well and limits the power of a discrete video card (GPU) that it can be paired with. Best choice here would be a GTX 1050 Ti, here are four for your consideration
https://uk.pcpartpicker.com/products/compare/RDQRsY,yprcCJ,ttQRsY,LrmxFT/
But before you order we would need to determine if your Power Supply Unit (PSU) has enough capacity. We don't need to consider connectors here as the 1050 Ti will draw all its power from the PCI-e x16 slot on the motherboard. Do you know what PSU you have? There will be a label with make and model on the outside of it.
We could also look at replacing your APU but there are no real upgrades available on the FM2+ platform so we would have to look at replacing your APU/CPU and mobo and most likely RAM as well. I tried to look at this but by time your pay for a G4560, B250 Mobo and DDR4 2400MHz RAM you only have enough money left from £350 to buy a 1050 Ti or spend more to get an RX 580 or GTX 1060-6GB (see build below). With the RX 580 build we would need to consider power connectors from the PSU.
I believe your options are:
■ Get a 1050 Ti. Lowest cost option (£115-£165), will be able to game well at 1080p medium to high settings.■ Get an RX 580 or GTX 1060-6GB. Cost range is £205-£300. These GPU's will be bottlenecked by the 7860K by the 7860K but you may see some performance improvement over a 1050 Ti. Power connectors need to be considered.■ Get a base GTX 1070 for £350. It will be bottlenecked horribly by the 7860K but would be unleashed if the APU/CPU was upgraded. Power connectors need to be considered. But I would only consider this option if you plan to upgrade the APU/CPU in the next six months and are considering gaming at 1440p.■ Spend a little more for the build below. This will game at 1080p ultra settings or at 1440p high settings. Power connectors need to be considered.
But before you do anything we need to look at your PSU capacity, it might have to be replaced in some or all of the options listed above.
G4560/RX 580 Build
PCPartPicker part list:
https://uk.pcpartpicker.com/list/ZBmDvV
Price breakdown by merchant: https://uk.pcpartpicker.com/list/ZBmDvV/by_merchant/
CPU: Intel - Pentium G4560 3.5GHz Dual-Core Processor (£55.98 @ Ebuyer)
Motherboard: MSI - B250M PRO-VD Micro ATX LGA1151 Motherboard (£61.80 @ Alza)
Memory: Team - Vulcan 16GB (2 x 8GB) DDR4-2400 Memory (£109.99 @ Overclockers.co.uk)
Video Card: Gigabyte - Radeon RX 580 4GB Gaming 4G Video Card (£206.75 @ BT Shop)
Total: £434.52
Prices include shipping, taxes, and discounts when available
Generated by PCPartPicker 2017-06-25 15:05 BST+0100