Make my LAN connected PC a wifi source?

Yes!

You need a wireless card in the desktop - which may be there if it's a relatively new one.

http://lifehacker.com/5369381/turn-your-windows-7-pc-into-a-wireless-hotspot/all

However, keeping your PC running to make a wireless hotspot for your iPad is energy expensive and noisy.

A small cheap wireless router will do exactly the same and you can leave it on 24/7

http://www.dabs.ie/products/edimax-n150-1t1r-wireless-router-9910.html?src=3

setup an adhoc network.

That's doable.

So buy a small USB WiFi dongle (€20 or less), plug it in and set it up. Set it up as a wireless hotspot, as detailed in the posts above. The last step in that guide talks about opening up your LAN to connections sharing.

BIG HUGE NB
If you work in a corporate environment, you could lose your job for doing this. What you're basically doing is opening up access to your corporate network to unauthorised devices and introducing a technically unsecured weak point to the network. In security terms it's like having someone break a hole in the office wall beside your desk and fit a door, for which only you possess the key (if any).

The preferred solutions to your problems are:
1. Ask for the password/access to the company's wireless network. Ask an IT person directly, don't log a ticket
2. If they have no wireless network and it's a small company, ask about adding a small wireless router so that phones and laptops can get access to email, and so forth. Be creative.
3. If it's a really really small company, show your boss how he could watch Sky Go on his iPad if he had a wireless network.
4. Watch Sky Go on your work PC.

Peterdalkey wrote: »

RE No 4 For some reason SkyGo does not like our network firewall and uses up 1 monthly connection change each time I use it!!

That changes things so
If you do the above, the network firewall will still be the problem because all your traffic is routed through it.

New option:

Buy a small wireless router, like the one I've linked to above, and put it outside your firewall.

So your network toplogy may look like this:

Internet <----> Cable/DSL Router <----> Firewall <----> (rest of network)

Do this:

Internet <----> Cable/DSL Router <----> Firewall <----> (rest of network) 
                                      |
                                       ---> Wireless AP

Pros:
You get wireless access directly to the web without compromising network security.

Cons:
There's now unfiltered wireless access over your web connection.