Warwick is generally considered one of the best maths department in the country, alongside Oxbridge and Imperial. Bath is also very good, although I think Warwick is really in a separate league to Bath. In terms of breadth in maths specifically Warwick has a wider range of options (Bath is a little more narrow). Whether "adding in" CS makes a difference is up to you - although it's worth noting there are several programming modules you can take in the maths course at Warwick which I believe are also fairly common options.
In terms of placements it depends on what you're aiming for - for software engineering and similar a good placement year can make a huge difference. However if you want to pursue investment banking or management consulting bear in mind Warwick is a target uni and Bath isn't, which does make a difference for those two specific areas. Outside of those in general your employability isn't really going to be linked to the uni so much, and a placement year would help but you can gain sufficient experience through appropriate internship etc.
Bear in mind the actual day to day life at each uni is going to be quite different - Bath being based in small city with a larger nearby city (Bristol) available to you, while Warwick is basically a suburb of Coventry and the nearest cities are Coventry and Leamington Spa (neither I think particularly known for their social or cultural scenes unlike Bath and Bristol). So that is worth keeping in mind.
Also consider if your Warwick offer requires you to take STEP.