whichever route you go, it would be a good idea to get on some real switches, and you can do that by using a very nice free switch lab at
its just switches, (L3) but you can do a lot of stuff
also check out the cisco offering, its only 100.00 and pretty good, using IOU 15 code images...so the same as working on real switch for the most part.
I have no experience with boson
The best network emulator on the market is the CCIE Lab Builder.
It is the same lab environment used in the CCIE but it can also be used for CCNP studies.
It has excellent Layer 2 and Layer 3 support. Furthermore it is cloud based so you can access it from anywhere in the world using a low end PC.
In addition the cost is very competitive.
I'm in exactly the same position but I've chosen CCNA Security, hoping that its a quick win, before starting CCNP, also self-funding. I've tried the Cisco Labs and Boson, I much prefer Boson. NetSim 10.8 runs on your PC, you don't need Internet connection. When I'm at home, I can plug in my second monitor and detach the scenario and topology windows to my second screen, leaving me a large open workspace on my main monitor. The Boson labs are excellent and much harder - if you do them all - than the real exam BUT you are not using Cisco IOS and the Cisco Lab environment is more aligned to an actual work environment.
I've just signed up for the Boson CCNA Security practice labs which are remote access into a Server environment, works well and seems really good, though it does take a while for the Windows Server instance to boot up. You must have an Internet connection for this.
I'm a big believer in directed study, especially for self study, you need something to guide you along the right path, otherwise you just end up bogged down trying to read 700+ page books. Boson NetSim and Exams really work for me, they take you through beginning to end. Then use your choice of books to read around and fill in the gaps. I tend to get Kindle books, then I can read them on my PC, on my phone or on my tablet, so reduces the weight I have to carry around when working away from home. Also the automatic bookmarking helps me pick up where I left off on a different device and I can read a consolidated view of my notes. I had a real downer on the Cisco Press CCNA level books but the CCNP level look better so I will give them a try in due course. I have the CCNA Security book for 640-554 but I'm finding it a bit dense for regular reading so I am using Chris Bryant's Udemy videos and dipping into the book when I need to.
I'm in the UK as well, buzz me if you want to Teamviewer into my PC and try one of the Boson labs at CCNA level.
The only problem with most simulation software is knowing exactly how far the simulation goes. In other words, what can't it do as opposed to what it can do.
The popular example here is Packet Tracer. It's a great learning tool, but there are issues that it has when trying to simulate certain IOS functions.
Another issue is command support. The developers of the simulation software my only allow you to configure certain things a specific way, or not support abbreviation of commands "sh ip int br" for example.
For professional level exams and beyond, I recommend trying your hardest to find some real gear or go for the CCIE Lab Builder (or even VIRL if you want to go down that path). Anything that allows full access to the IOS command-set.