They may be lenient, however Bath are not known to let up when it comes to entry requirements. If you firm that offer, you may not get in once you get your results, did you apply to any other universities? What are they offering you? You should have a back up University (insurance choice) which has slightly lower entry requirements just in case you don't meet the requirements for your first choice.
As for placements, you can do the 3year course now and switch to the 4year placement course at the beginning of the second year if you want to do placements, it shouldn't be hard to get placements, and the University are able to help you find somewhere.