Dobsonian Wellingtonian

Hi, first time poster here. I had a Heritage 150p for Christmas last year, and have been using it whenever possible in the UK. Aside from the 10mm and 25mm eyepieces that come with the scope, I bought a 2x Barlow, and a Skywatcher 4mm 58° planetary. I've been able to get reasonable views of Jupiter and Saturn with my planetary, but was looking for something that might give an even better view. I'd seen a recommendation for a 52° 6.5mm planetary from Explore Scientific, but they appear to be sold out everywhere online, with no real indication of future availability. I just wondered if anybody could recommend a good alternative to this lens for planetary views for use with the 150p at all please?