Why you need UK hosting?
It actually depends from where the majority of your site’s traffic is generating. You can know it by configuring Google Analytics on your site. If the big volume of your traffic is coming from inside Europe or Africa then UK hosting is ideal but if majority of the traffic is from North America, South America or regions like Australia then you should opt for US hosting. As many European companies prefer to host their data inside EU to ensure its protection - and UK hosting fulfills that requirement.
Websites getting their visitors from different regions can split their hosting between both UK and US locations. If you are also having such type of site then you can easily search out companies offering this smart move. For example, you can get your Reseller Hosting Plan in the US whereas other plan in UK.

Advantages with UK hosting

Higher placement in UK search engine's Rankings: If you are hosting your website with any UK host and addressing mainly UK audience then you will get a good ranking in UK search engine listings because search engines consider this thing if an account is created at the same region where the target audience is located.
First class technical support: UK hosting companies mostly don’t outsource their support to third party firms or off-shore firms -this means you will receive the best possible support. You and the support staff will be in close interaction and the matter will be solved quickly. But, always make it sure because there are few UK hosting companies outsourcing their web hosting support.
Fast connectivity: UK companies working with UK hosts always get a faster connection. The visitors residing in UK will load the site much faster.

Disadvantages with UK hosting

In the disadvantages section, I have come up with only one; there may be some more also but this is the major one.
Cost: Hosting is substantially cheaper in US as compared to UK. UK companies charge heavily due to the higher cost of resources in UK like bandwidth and disk space. The costs of the buildings (where the servers are placed), staff pays, electricity, heating and phone lines all are costly in UK and this raises the prices up. Same services are cheaper in other places, where costs of such resources are low. E.g., US web hosting services are low in their prices than UK services because bandwidth and server hardware is available at comparatively low rates there. The only reason is most of the equipment is manufactured in USA.
Even then, I still consider UK hosting better for UK websites. It makes communicating with the hosting company easier and better in targeting audience in the search engines. Also, it is always good to set up your business closer to your home. So, if anybody asks me - Will UK hosting prices ever reduce as low as the US? I will be confident to say, not in the next decade anyway. However, UK hosting plans are same to the US hosting plans; the only difference is that UK hosts charge in GBP rather than USD.

How to reach right UK hosting company?
There are sites writing reviews on different UK web hosting services and their packages. Real clients and customers are also involved in writing such reviews; they give honest opinions based on their personal experiences with those UK web hosting companies. These sites are the best place to learn about the UK web hosting services because these users, who enjoyed their services, are the best judges. These reviews are also written by the men in industry; these people are professionals and especially the ones who are in the industry or somehow related to the web hosting field.