Keil does support the LPC (NXP processor family) of chips. Also, IAR supports them and there is a free evaluation version (32K code size limitation) available from either vendor - or at least, IAR is still offering this for free which is prefectly good for starting out. Another advantage of using the LPC ARM7TDMI family of chips is with the Segger or IAR J-Link programming/debugging pod and the LPC2xxx target processors, the IAR toolset with automatically give you unlimited software (program flash) breakpoints, instead of being limited to the usual (2) breakpoints as allowed in the early ARM interface. Having all these software breakpoints is very useful and extremely helpful when debugging/learning.
There are other tool suites available on the internet, including the GNU /Eclipse based tools, which are free to use but require alot of setup which you may or may not be able to do. There is also Rowley Crossworks which has some lower-cost purchase options. I am most familiar with (And use) both the IAR tool suite and the Rowley Crossworks tools myself.