For "basic" office type use I would go for an Intel i3 CPU. The link above to the Lenovo is for a Pentium CPU which are OK but an i3 probably would be better. An i5 is better but more expensive, an i7 is even better but even more expensive.
For memory got for 4GB minimum, or 8GB if you can find it. But for basic use 4GB is enough.
Most PCs come with huge hard disks nowadays 500GB or even 1TB so that is plenty of room. Some PCs come with an SSD (Solid State Drive) nowadays they are smaller, say 250GB, but will be a lot faster than a hard disk.
Any modern PC will have Windows 10 Home on it.
Some companies are phasing out DVDs so if that is important to you then make sure it has a DVD.
Some desktop PCs have wi fi built in and while you may not need it if you are connected via a cable it is still a "nice to have".
Be wary of PC World as they will try to get you to buy all sorts of add-ons you don't need (for extra money of course).
I have had a number of Dell PCs and they have all been fine. You can order them online from the Dell web site so wont get pressured in to buying lots of extras.
Inspiron PCs are good from Dell
http://www.dell.com/uk/p/inspiron-3650-desktop/pd?ref=PD_OC
Or go to the Dell Outlet site where they sell out of date PCs or returned PCs (or PCs that are not selling) for a reduced cost. I have bought a few off there and they have been fine
But if you see one on there grab it quick as they dont stay on there long.
http://outlet.euro.dell.com/Online/InventorySearch.aspx?brandid=1&c=uk&cs=ukdfh1&l=en&s=dfh&frid=147&~ck=mn
Of course if you want to play games or do other specialist work then you need to look at the specs carefully and consider the graphics card that is installed. All the above specs I gave you are for an "office" PC